Domestic B2B (and B2G) for all Polish VAT taxpayers, both VAT-active and VAT-exempt. B2C remains voluntary with no announced mandatory date. Foreign entities with a fixed establishment in Poland involved in the supply are in scope; entities merely VAT-registered without an establishment are generally outside the issuing obligation but can be given KSeF access.
Two traps. (1) The '2027 deferral for the smallest businesses' is far narrower than people assume — it only covers taxpayers whose invoices are each under PLN 450 AND whose monthly sales are under PLN 10,000; almost every real micro-business was already in from 1 April 2026. (2) The penalty holiday is a holiday, not a delay: the obligation is legally live now, invoices without a KSeF ID are not validly issued, and only the fines are suspended — and only until 31 Dec 2026. Also flag 'Offline24' mode (permanent contingency issuing, with mandatory upload afterwards) as the operational detail that decides integration design. Poland deferred KSeF twice before (July 2024 → Feb 2026), so past-deferral scepticism is understandable, but it has now actually happened.
4 of 6 are primary sources. Mandate dates move — treat this page as a starting point and confirm against the primary source before committing a plan.
A page is a starting point. A scoped analysis gives you the specification, the mapping and the effort — in weeks, not quarters.
